i use a 9600 interrupt driven full duplex bitbang rs232, but there is not much time left to do anything else, while there is full duplex traffic. this runs on a 16f876 @ 4mhz. tino Olin Lathrop Gesendet von: pic microcontroller discussion list 26.03.03 13:25 Bitte antworten an pic microcontroller discussion list An: PICLIST@MITVMA.MIT.EDU Kopie: Thema: Re: [PIC]: Max bit bang serial on 4Mhz 16F876 > Before I go off and waste a bunch of time trying to do the impossible > (but hey it may be fun), does anyone have any advice on what is the > fastest half duplex rs323 comms I can expect to get using software only > on a 4MHz 16f876 (using a resonator not a crystal)? I once did a 9600 baud software UART on a 16C62A running at 160KHz. That was pushing the limit because it worked for transmitting, but receiving was unreliable because of the measurement jitter on the leading edge of the start bit. Scaling that up to 4MHz oscillator comes out to 240Kbaud. That means 115.2Kbaud should be quite doable assuming your oscillator is accurate enough. My code required constants for the oscillator frequency and the desired baud rate, and a bunch of assembly time computations automatically produced the code. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body